Unable to see, select or edit new objects
You may need to look a little harder at the outliner objects.



If the little eyeball next to the hidden objects is off, then the object will be hidden in the viewport.

If this is the case then with your mouse cursor over your 3D viewport, Alt+H will turn this back on for these objects.

Also you may need to check if you are currently using the scene's active layer...

If your 'Lock camera and layers' button looks like the following, you will want to click it to toggle the lock.



Related to the last comment, you may need to hit ` (Backtick) to toggle all of your layers on.

Otherwise the only other thing that I can think of is viewport clipping.



If you are having trouble getting to this panel, with your mouse cursor over the 3D viewport hit the N key to toggle.

Then try increasing your clip distance.

You may also have to do the same for your camera for rendering, but that setting will be found in the properties panel >> Object Data >> Clipping